Projection apparatus.



J. B. TAYLOR-.

v PROJECTION APPARATUS. APPLICATION FILED FEB. 17, I915.

13%975 1 19mm Jan. 30, 191?.

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JOHN B. TAYLOR, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROJECTION APPARATUS.

misses. Original application filed 11111623, 1915,

No. 35,768, filed June 23, 1915,) of whichthe following is a'specification.

My present invention relates to projection apparatus and especially to incandescent lamps adapted for utilization with such apparatus.

The object of my invention is to provide an incandescent lamp of special construction and so to arrange it in relation to other apparatus employed therewith that it will provide a concentrated source of light of sub stantially uniform intensity which will be suitable for projection and similar purposes.

One of the principal requirements for a light source for projection purposes'isthat it shall be of high intensity and concentrated in a small area. Another requirement is that the intensity of the light shall be substantially uniform throughout the entire area of the light source. electric arc has been commonly employed because of the fact that it furnishes a con centrated source of light of high intensity and one which gives substantially uniform illumination over the area on which it is projected. Incandescent lamps as heretofore constructed have not been suitable for projection apparatus because they have been lacking in the principal requirements above I stated. The light emitted by vacuum lamps employing the usual straight filaments of carbon or tungsten is not of suflicient intensity and is scattered over too large an area to be employed successfully for this purpose, In lamps having a filling of inert gas the metal filamentymay' be operated at a much greater intensity. When the filament is coiled or spiraled according to the usual construction in such lamps the source of light is also much more concentrated. If the coilsor spirals are fairly close together the effective light emitting area in any direction is practically the same as that of a I fiatfilament-whose width is equal to the diameter of the coils. structedhowever such lamps have not been entirely satisfactory for some purposes, such,

Specification of Letters-Patent.

Heretofore an- As heretofore con- Patented J an. 80, 1931?.

Serial No. 35,768. Divided and this application fiIed February 17,

1916. Serial No. 79,001,

for example, as for the operation of moving picture apparatus. If the usual looped filament of V-shape is used the image of the filament will appear on the screen as a \l-.

shaped streak of light'of much higher intensity than the. remaining portions of the screen and if a reflector is used behind the light source the reflected image will appear on the screen as another l-shaped streak of light of comparatively high intensity, in-

verted with respect to the direct image. have found, however, that by constructing a lamp in which the coiled filament is divided up into a plurality -of sections parallel to each other and all in the same plane, the distance between adjacent sections .being about equal to the diameter of the coil the above mentioned difiicultymay be overcome and asubstantially uniform illumination of the screen obtained. In securing this result the lamp should be so adjusted with respect to a refiectorthat therefiected image of the filament sections will fall, on the s'creenbetween the direct images and the only streaks whichcan be observed on the screen under any condition will be due to the difference in intensity of the direct -and reflected images. With an-efficient reflector these differences are not in most cases sufiiin connection with the accompanying drawing in which Figure 1 illustrates diagrammatically the application of a lamp, constructed in accordance with my invention to moving picture apparatus; Fig. 2 is a view of the lamp filament; Fig. 3 shows the relation of the direct image of the filament and the reflected image when the projection apparatus is properly adjusted and Fig. -l is a view of a lamp constructed in accordance with my invention.

-As shown in the drawing the lamp comprises the usualbulbl having a screw'base nected. The filament 5which is connected 2 to which the leading-in wires 8,4 are conto the leading-in wires is preferably of tungsten and consists of four closely coiled sections 6, 7, 8 and 9, all arranged in the same straight connecting portions are made of such length that the distance between adjacent sections is substantially equal to the outside diameter of the coils. A support 11 secured to the leading-in Wire 3 but insulated therefrom by a globule 12 of glass may be employed for supporting the filament at its middle. If desired other supports may be provided at other points in the filament in order that the sections may be securely held in thedesired plane during the operation'of the lamp. The bulb 1 is preferably filled with an inert gas such as nitrogen or argon.

In employing a lamp such as I have described in co apparatus the lamp is so adjusted that the center-of curvature 13 of the spherical reflector 14 "is of the same plane as the filament and at one side of one of the central sections near its middle point. -When thus arranged section 6 is reflected so that its reflected image occupies the. position 6 between sections 8 and 9, section 7 is reflected so that its image occupies the position 7. between-sections .7 and 8 etc. Thus it will be seen that the filament and the reflected image of the filament combine to give the efiect of a practically continuous light source in the plane of the filament. The point 13 is also on the optical axis of the condensing lens 15 which concentrates the light and directs it through the aperture 16, in front of which the film 17 is caused to pass. The light then passes through the .projecting lens 18 and the pictures on the film are projected upon the screen 19. 1

While I have illustrated the preferred form of lamp and one application of the lamp described it will be apparent that.

nnection with moving picture many modifications may be made in the structure of the lamp and its application without. departing from the scope of the appended claims; for example, it will be apparent that a similar effect might be secured with a straight filament having a plurality of parallel sections spaced apart a distance equal to the diameter of the filament or with a ribbon-like filament having sections spaced '50 apart a distance equal to the width of the ribbon.

What I claim as new and desire to secure by Letters Patent of the. United States,

1..An. incandescent lamp for projection purposes having a coiled filament made up ofa plurality of parallel sections all in the same plane and spaced from each other a distance approximately equal to 'the diam eter of the coils. I

2. An incandescent lamp for projection purposes having a. filament made up of a plurality of parallel sections all inthe same plane, the area in that plane betweenadjacent sections being substantially equal to the efiective light emitting area of a single section in a direction normal to the plane of the filament.

3. An incandescent lamp for projection purposes comprising a bulb having a filling JOHN B. TAYLOR. P 

